The present invention relates to a pneumatic tire which can increase a winding working efficiency at a time of forming a side wall rubber and a clinch rubber in accordance with a strip wind method, and can inhibit a turbulence of a rubber strip, and a manufacturing method of the same.
In the pneumatic tire, a conventional step at a time of forming the side wall rubber and the clinch rubber is shown in FIGS. 7(A) to 7(D).
As shown in FIG. 7(A), in particular, a composite rubber body b comprising a side wall rubber b1 and a clinch rubber b2 which are integrally extruded from a rubber extruder is wound around a region on a former a and in both ends (FIG. 3) of a former a at one circle. Thereafter, as shown in FIG. 7(B), a carcass ply d is wound between the composite rubber bodies b and b at one circle while being bridged.
Further, as shown in FIG. 7(B), a bead core e is set on an overlapping portion between the composite rubber body b and the carcass ply d. The carcass ply d is inflated in a toroidal shape between the bead cores e and e. Prior to this, a tread ring f (including a tread rubber f1) which is separately formed so as to constitute the tread portion is awaited in an outer side in a radial direction. The carcass ply d presses the inflated portion to an inner surface of the tread ring f so as to stick thereto together with the inflation, thereby integrally connecting. Further, a portion j protruding to an outer side in an axial direction of the former from the bead core e is wound up around the bead core e, and is pressed and stuck to a side surface of the toroid-shaped carcass ply d, whereby the side wall portion is formed (FIG. 7(D)).
On the other hand, for example, Japanese Published patent application No. 2000-254980 and the like have proposed a method (a so-called strip wind method) of forming a rubber member such as a side wall rubber, a clinch rubber, a tread rubber or the like by a strip wind body formed by winding a long rubber strip so as to overlap in a circumferential direction and spirally. In this method, since a large-size rubber extruder is not required, and it is not necessary to store an extrusion molding body for the rubber member as an intermediate stock, it is possible to obtain a great advantage especially for a tire which tends to be manufactured in a large item small scale production, such as achieving space-saving, and the like.
However, in the case of forming the side wall rubber and the clinch rubber corresponding to the composite rubber body b by using the strip wind method, in the raw tire forming step mentioned above, it is necessary to sequentially wind two kinds of rubber strips having different rubber compositions, finish forming one rubber (for example, the clinch rubber), and thereafter form the other rubber (for example, the side wall rubber) so as to be connected to an end portion of the one rubber.
Accordingly, a time is required for winding, and a production efficiency is deteriorated. Further, in a step (FIGS. 7(C) and 7(D)) of winding up the protruding portion j and pressing to the side surface of the toroid-shaped carcass ply d, the cylindrical protruding portion j is deformed in a disc shape, however, an elongation in a circumferential direction is increased at this time in accordance with being apart from the bead core e in a radial direction. Accordingly, the turbulence is generated in winding the rubber strip, and there is generated a tendency that an outer appearance quality of the tire is deteriorated.